InGaN laser diodes with 50 mW output power emitting at 515 nm

Abstract

We demonstrate direct green laser operation from InGaN based diodes at wavelengths as long as 515.9 nm with 50 mW output power in pulse operation. A factor of ∼10 defect reduction for the In-rich InGaN quantum wells based on improvements of the epitaxial growth process and design of the active layers on c-plane GaN-substrates makes it possible to demonstrate laser operation at room temperature. Micrometer-scale photoluminescence mappings and electro-optical measurements confirm the reduction of nonradiative defects in the emitting layers. The 11 μm broad-area gain-guided laser structures were driven in pulse operation to minimize thermal effects and to accurately measure the laser temperature dependence. The threshold current density was ∼9 kA/cm2 and the fitted slope efficiency had a value of ∼130 mW/A for an optical output up to 50 mW.